The prior art demonstrates a number of devices to aid in the drawing of geometric shapes and angles. U.S. Pat. No. 405,432 to Pratt discloses a device having a base to which is attached, by means of a bolt, a rectangular plate. The bolt is transversely slotted to accommodate a blade. The plate is provided with a slot which adjoins the slot of the bolt to allow the blade to slide in the aforementioned slots for purposes of linearly adjusting the blade. The plate is pivotable about the bolt to allow for rotation of the plate upon the base.
U.S. Pat. No. 458,606 to Weaver discloses a T-square having a blade upon which is provided a slotted plate for allowing rotation of the blade about a screw which is situated upon a head or base member. U.S. Pat. No. 970,625 to Krajicek discloses a T-square which is provided with a longitudinal slot. A slide piece is slidable along the length of the slot and is connected to a disk. The slide piece and disk allow a rule to pivot within and slide along the longitudinal slot.
U.S. Pat. No. 1,139,648 to Demmer discloses a combination tool having a scale which can be adjusted linearly and rotated about and to the side of a center pin. U.S. Pat. No. 530,060 to Amos discloses a T-square having a bar which is pivotally connected within a slot of the T-square so as to be linearly adjustable. U.S. Pat. No. 2,412,084 to Gieske discloses a protractor having an arm which can be adjusted linearly and rotated about a stud.
However, notwithstanding the prior art, the present invention introduces a drawing aid device which is simple in construction, economical, more easily adjustable than prior art devices and quickly adaptable for use on either side of an object to be drawn on.